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  1. #1

    Default Keep and tune the Keihin butterfly or swap

    I know there's lots of threads on this on chopcult and other forums but there not exactly up to date. But I have been searching.

    My 84 FXR with the stock 80" evo just bought, wasnt idling right so I started taking the carb apart and found the carb was dirty and the compliance fitting intake has a big rip in it so I guess that explains the not idling or running right.


    Anyway I'd like to get a solid intake, I'm looking at a Ram Jett right now and I think it will bolt right up to my carb. it's a Ram Jett E. Is there any better options still being made that will match up to my carb?

    I wanted to rebuild my carb and add a Andrew's accelerator pump kit, but they stopped making them a while ago so is this carb worth running without the accelerator kit? And my idle mixture screw is still plugged so I need to unplug it.

    The main thing is before I buy an intake manifold, jets, gaskets, and a rebuild kit is there a better option or should I just go ahead and buy the Ram Jett and rebuild my carb?

  2. #2
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    lot's of choices out there, what do you want out of a carb,
    obviously rebuilding is the cheaper option if you want stock & are happy with how it ran.
    if you want to up-grade it there are a lot of ways all good depending again of what you want out of the bike & how much money you want to spend.
    if you want easy starting & an all round good everyday riding carb the HD CV carb conversion is a good choice,
    or the SU was always a good reliable carb,
    but if you want to go reliable WITH performance gains, then either the Mikuni HSR or the Lectron (My Personal choice !!)
    Carbs have come a long way from the days of a soup can feeding gas, to what's available today,
    I like to run the most efficient easy to fit & use, but hi-tec carb I can get, so the Lectron did it for me.
    fix it as is for $75 in parts or drop $700 for all the whistles & Bells or drop $100-$200 for a good all rounder..

  3. #3
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    Get the Ram Jett. (Pic is my FXR engine hanging from a sling on the intake. Do THAT with a stocker!)

    I threw the stock rubber boot intake in the trash when I bought my '88 FXR new. There is no better intake than Ram Jett for an Evo. Cut your own gaskets from Fel-Pro gray material (any auto store). I run the Ram Jett with any carb. It fits the Keihin which I used until I replaced carb and camshaft.

    We used to drill the low speed jet one drill shank (always measure using clean drill shanks, not the fluted end) larger the largest that's a slip-fit. Ya can aim the accel pump squirter so the stream is centered since it's pressed in. V-Twin made a repop of the Andrews which was a repop of the older stock parts (Shovelhead, Ironhead era, if ya shake the cover and it rattles that's the right one). 35-9050 is the number. #60-thru 80 drill bit sets are a few dollars online. Clamp bit in visegrips or a pin vise, spin jet between thumb and forefinger to drill then stroke a couple times without spinning to debur.

    That said there are plenty of carb choices. CVs fit a Ram Jett with a rubber boot or alloy flange adapter, S&S bolt on though I had one where I had to widen the manifold bolt holes, Ram Jett made quite a variety.

    Bang for buck a rebuild is good but play with jetting since they were lean from the factory. A better carb is the later CV and because Ram Jetts don't need a carb brace the single rubber boot adapter or the press-on flange will do. I'd go for the alloy flange kit for shorter length.
    Attached Thumbnails Attached Thumbnails Ram Jett sling lift.jpg  

  4. #4

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    I'm surprised that any of the compliance fitting intakes are still around. The later manifold and flange style was the common upgrade. S&S offered a kit for the upgrade. I don't know if there is an H-D later style manifold that will accept your butterfly carb or not, so some sort of aftermarket manifold will be needed.

    Nothing wrong with keeping the stock carb. With about a .75 - .78 intermediate jet and a 1.70 - 1.75 main, and an idle screw adjustment it should run well. I think these carbs get a bad rep because people don't take the time to tune them.

    Jim

  5. #5

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    Tzienlee, I'm gonna run the stock carb for now but may upgrade to a Mikuni later on. Like Farmall said I can run different adapters for different carbs on the Ram Jett.
    I havent rode the bike enough to really decide what to run yet. Especially with the bike running so poor. Thanks for your input though! I'd love to check one of those Lectrons out one day after getting my pipe and air cleaner on this thing and getting it on the road.

    Thanks Farmall just who I wanted to hear from, I read your post from the V-twin forum and some stuff on here about the Ram Jett. My compliance fittings are toast so Ram Jett it is.

    I'm gonna rebuild the butterfly as well and get it tuned in. Thank for the Acellerator pump part number I'll have to get that as well, do you drill the float bowl st the same place as the Andrew's?

    Thanks for the jetting info Jim. The jets in the carb are, main:165 intermediate: 65 running a foam insert air cleaner and drag pipes. I'm gonna be running a 2 into 1 pipe and not sure what air cleaner yet. Anyway I was thinking around the same jetting as what you said.

    One other thing if anyone can chime in
    The plugs in the bike were gapped to like .033 and pretty fouled so I threw in a new pair and gapped them to .040 as that's what I read they should be gapped at was this a good move? Running a S&S Hi-4N ignition.

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    Float bowl drilling will be the same but check since I don't remember if your '84 is already drilled or when the castrated cover superseded the one with the check ball.

    Post what ya find out to help the next fellow. Got pics of the old plugs? Just carbon fouled? The gap should be fine.

  7. #7

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    Quote Originally Posted by farmall View Post
    Float bowl drilling will be the same but check since I don't remember if your '84 is already drilled or when the castrated cover superseded the one with the check ball.

    Post what ya find out to help the next fellow. Got pics of the old plugs? Just carbon fouled? The gap should be fine.
    I'll double check before I start drilling, mine is the one with the plastic choke cam thing on the side, I think the predrilled ones are pre 1978 or something like that.

    While I was riding the bike home from purchasing it, the air filter sucked into the carb and I may have fouled the plugs out trying to get the bike started again, I didn't think to check the air cleaner. so I limped the bike home barely running cause i didnt know the carb was stuffed full of filter.

    You would think the plugs would show signs of being lean if the bikes running drag pipes, had a intake leak and a .165 main and .65 intermediate I read that was the stock jetting sizes. But I also read. 150 main and .50 intermediate somewhere else. Maybe underneath all the fouling it shows lean conditions.

    I added up everything and its gonna be about $250
    For:
    -Ram Jett intake
    -idle jets: .72 .75 .78
    -main jets: .170 .175
    -rebuild kit
    -accelorator pump kit
    -extended idle mix screw ( this is $30 with shipping so might not get it to save some money)
    -brass fuel inlet
    -gasket paper

    I think that's all I need, let me know if I'm missing something anyone.

    I appreciate everyone's help I'll post what happens when I get it all cleaned and together.

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    I abominate foam filters as they disintegrate over time (I've picked the debris from many customer bikes) and (not common but worth knowing) are poor flame arresters. Customers would fry theirs now and then. Foam is fine for an additional filter sock for dirt bikes but that's utterly pointless on the street.

    OTOH I have K&Ns over thirty years old whose rubber remains supple and work fine.

    I never bothered with any but the stock idle mixture screw as they're a "set it and forget it" item. I use a flat tip screwdriver with a "hollow ground" bit (see pics of gunsmith screwdriver bits) and never a common garbage cheap "wedge" tip which only exist because they're cheap to produce.

    You can easily grind the best contour for a brass jet screwdriver on any old round shank screwdriver after cutting off the tip or by modding a hollow ground replaceable bit. The ideal tip for soft metals is not the hollow ground type but that's the best commercially available type. I shorten long drivers for tank clearance by slicing 'em off with a zip disc.


    The best looks like )( from the side. That style does not smear brass jets or screws. Do the work NEATLY. A Dremel (wear eye protection) hose clamped to a hunk of metal clamped in a bench vise makes a nice high speed fine grit grinder. It works better than holding the bit in a vise since securing the Dremel is less awkward, but if you freehand the Dremel clamp the bit so you can precisely control the Dremel like two-handing a welding stinger.

    My mentor came up with the idea in the '60s and I've never seen anyone else use it but it works a treat on any common screw head. I buy various common screwdriver bits in different lengths to mod but started off modding screwdrivers. The bits are generally better material and already have the right cylindrical cross-section. They are not for heavy use as grinding thins the tip but are perfect for soft metals.

    Always match your tip to the slot you're dealing with. Little details make wrench life easier.

  9. #9

    Default

    Thanks for all the tips Farmall no pun intended, I dont plan on keeping this Foam filter air cleaner but I'm not sure what I'm gonna run yet.

    I usually use JIS screwdrivers for the Philip's style screws on carbs and I'll try to make sure I use the hollow ground screwdrivers from now on. I have tons of bits laying around I can modify also If I need to.

    I will post some pics of the plugs when I get home,
    I've already cleaned them up a bit though so dont know if they're readable.

  10. #10

    Default

    They're kinda sooty and I cleaned a lot of the carbon off the other day, but I think that's from me fouling them out. underneath they look pretty lean looking to me, but I havent been messing with bikes long enough. so tell me what you think anyone?

    My mistake on the jet sizes that were in the carb
    After checking again: Main: .170 intermediate/Pilot jet: .45

    If the stock jetting for this carb Is: main: .165 and
    The intermediate/pilot: .50 or I read it could be .52.

    Should I get .170 .175. For my mains, and .52 .55 .58 .60 instead of .72 .75 .78. wouldnt those be a little too rich?


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  11. #11

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    I run the factory CV carb on my 1995 evo big twin. To be honest, Ive only ever used CVs whether its on a 70s chop or a more modern evo.
    I find them very easy to work on and you can dial them in great to match your performance mods. My dad had a Mikuni HSR on his evo and it was a very smooth carb. If I ever decided to try anything else I would probably spend the coin on one of them, however I have no reason to at the moment as my CV does just fine.

    When I was running just stage one screamin eagle air cleaner kit and aftermarket mufflers on stock headers with the crossover pipe, the carb had a 42 low jet, 175 main and stock needle. It needed plenty of choke to start but once up to temp it ran just fine.

    When I put a paughco full system (with baffled mufflers) and an EV27 in it, I bumped the low jet to 45, main jet to 190 and added a CV performance velocity needle. Bike starts on 2nd kick every time, idles well, no carb coughs and pulls like a freight train all the way up the rev range.
    Last edited by Sugarcubes; 07-19-2021 at 6:45 AM.

  12. #12

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    Quote Originally Posted by SaddleTramp98 View Post
    They're kinda sooty and I cleaned a lot of the carbon off the other day, but I think that's from me fouling them out. underneath they look pretty lean looking to me, but I havent been messing with bikes long enough. so tell me what you think anyone?

    My mistake on the jet sizes that were in the carb
    After checking again: Main: .170 intermediate/Pilot jet: .45

    If the stock jetting for this carb Is: main: .165 and
    The intermediate/pilot: .50 or I read it could be .52.

    Should I get .170 .175. For my mains, and .52 .55 .58 .60 instead of .72 .75 .78. wouldnt those be a little too rich?


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    plugs look ok but if it was me, I would probably back the idle mix screw out a quarter turn to lean it out slightly. Its probably too much choke when starting / sitting in traffic thats darkening em up a little.

    Elec ignition plug gap is normally listed as 0.35-0.40
    Last edited by Sugarcubes; 07-19-2021 at 6:46 AM.

  13. #13

    Default

    Yeah after looking at them, the plugs look pretty decent under all the soot. When the air filter was stuck in the carb I fouled them out messing with the choke trying to get it started.

    I have everything ordered, hopefully everything shows up by Saturday. I got the plug out for the idle mixture screw and drilled out the new hole for the upgraded accelerator pump. I even went ahead and picked up my Supertrapp exhaust.

  14. #14

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    get it all back together when your parts arrive and take the bike out for a good run on open road so you can get a feel for the power delivery through the rev range. pull over after 20 miles or so of traffic free riding and check your plugs.

  15. #15

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    So bad news I bought and Accelerator pump kit from the only place I could find it, and they cancelled my order today and said it was out of production. This was a V-twin manufacturing part that I ordered so I'm guessing it's no longer made.

    I already drilled the hole for the new pump so will my carb work as is or do I need to plug that hole I drilled? or does anybody know where I can get a accelerator pump that will work.

  16. #16

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    Quote Originally Posted by SaddleTramp98 View Post
    So bad news I bought and Accelerator pump kit from the only place I could find it, and they cancelled my order today and said it was out of production. This was a V-twin manufacturing part that I ordered so I'm guessing it's no longer made.

    I already drilled the hole for the new pump so will my carb work as is or do I need to plug that hole I drilled? or does anybody know where I can get a accelerator pump that will work.
    I believe Andrews previously made the kit and V-twin may have copied it. Andrews show it as discontinued on their site but you could try Dennis Kirk or JP cycles to see if they have any of them or the Vtwin version.

    Some folk remove the choke plate and shaft that's in the mouth of the carb and plug the shaft hole. That removes some of the obstruction in the air passageway, equivalent to having a 2mm larger carb if you believe the performance books. Leave the choke cable and linkage intact, so you still have a fast idle option while it's warming up.

  17. #17

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    I've looked up both the V-twin part and the Andrew's, using parts numbers and just " Andrew's accelerator pump kit" or " Vtwin manufacturing Keihin accelerator pump kit" pretty much everywhere including J&P and Dennis Kirk, Ebay, Amazon. All I get it is "Sold out" or "out of production". I dont believe it's coming back either.

    I'm just gonna try to see if the stock accelerator pump will work with the hole I drilled. if not I'll JB weld it and just run it with the stock accelerator pump cover.

    I don't plan on removing the choke plate I'm not looking for performance. I just wanna make the bike start without killing the battery trying and not have to feather the throttle at stop lights to keep it going.

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    A drilled hole absent the check ball will have the reverse of the intended effect so best to JB and return the bowl to stock (or if in no hurry ask on Fecebook parts forums and here if someone has one as they'll likely damn near give the carb away. (We used to make Sportster owners happy that way replacing their worn out Bendix/Zenith carbs.) Every biker should have a matching clean known-good test carb as part of their troubleshooting kit (when I began treating personal work like fleet and aircraft maintenance my life got MUCH easier which I like as I'm lazy) anyway, just don't pay much for one and ensure the seller inspects the pump cover by removal.

  19. #19

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    Quote Originally Posted by farmall View Post
    A drilled hole absent the check ball will have the reverse of the intended effect
    Thanks Farmall, that's what I needed to know. JB weld it is, I can always drill it out again later. I may upgrade carbs one of these days but I'll hang on to this one too.

  20. #20

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    Ive been sick but I'm better now and I got my new to me Ram Jett intake on, my new Supertrapp 2 into 1 exhaust on and the carb cleaned and jetted. Main: .170 and pilot .75, idle screw 1.5 turns out. The bike fires up with zero choke on the first crank now. versus killing the battery trying to get it to start before.

    It's running a little rich with this setup, I think I'll go down to .165 on the main jet. With a little more tuning I should have it dialed in. I still need to replace the leaky fuel inlet though.

    Thanks for all the help everyone. Hopefully this will help someone in the future with the same problems as me.

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